#!/usr/bin/env bash
#
# Usage
# -----
# $1 means 1st commandline argument, $2 second etc.:
#    $1=output interface (defaults to eth0)
#    $2=input interface (defaults to eth0)
#    $3=payload length of eth. frame in bytes (42...1500, defaults to 256)
#    $4=number of packets
#
# Output format
# -------------
# Colum number
#	1	Timestamp
#	2	Packetloss at 10MHz [%]
#	3	Packetloss at 5MHz [%]
#	4	Number of packets in a batch
#	5	Number of bits in packets susceptible to bit flip
#
# Requirements
#-------------
#
#    * Root access to the machine
#    * The interface must be in the up state (and not the down state).
#    * The interface must support full duplex and must be set in full duplex
#	mode
#    * Ability to install software
#    * No fiddling with IP address and/or ARP entries necessary.
#    * GNU/Linux operating system
#    * A single free network card dedicated for the test
#    * There must not be any traffic on the network card at all, including 
#	ARP requests. Any traffic will cause deviation in reading.
#
# Step by step procedure
#------------------------
#
#    * Ensure you have installed GNU grep version at least 2.5.
#    * Ensure the network card dedicated for the testing is in full duplex 
#	10Mbps-only mode (see RonjaFullDuplexHints)
#    * Connect a hardware that will send the data back to the same or
#       different network card
#    * Run the pktloss script. It will print out packetloss immediately, 
#	accurately and automatically. 5 columns of numbers will be infinitely
#       printed. They mean:
#        1. time stamp
#        2. 10MHz packet loss
#        3. 5MHz packet loss
#        4. number of packets in batch
#        5. number of bits in ethernet frame effectively susceptible to bit flip
#        Each row means one batch run.


# Configuration: edit the iface and cont below to set up the script
#
iiface=eth0 	
oiface=eth0
count=1024
# Minimum payload is 42 and max. 1500
payload=256
#payload=42
# End of user-configurable data

if [ `whoami` != 'root' ]
then
	echo "Error: you must be root to run pktloss." >&2
	echo "Run su and enter your root password and then rerun the pktloss script again." >&2
	exit 3
fi

if [ $# -ge 1 ]
then
	oiface="$1"
fi
if [ $# -ge 2 ]
then
	iiface="$2"
fi
if [ $# -ge 3 ]
then
	payload="$3"
fi
if [ $# -ge 4 ]
then
	count="$4"
fi

if [ "$payload" -gt 1500 ]
then
	echo "Payload length too much: maximum 1500." >& 2
	exit 1;
fi
if [ "$payload" -lt 42 ]
then
	echo "Payload length too short: minimum 42." >& 2
	exit 1;
fi

nbits=`echo "($payload+4+6+6+2+4)*8" | bc` # Only half preamble is assumed
                                           # sensitive to bit flip

ifconfig $iiface up
ifconfig $oiface up
rx0=`netstat -in -f link -I $iiface | tail -1 | awk '{print $5}'`
tx0=`netstat -in -f link -I $oiface | tail -1 | awk '{print $7}'`
while true
do
./bertest $count "$oiface" $payload 0
sleep 0.05
date=`date +'%s.0'`
tx1=`netstat -in -f link -I $oiface | tail -1 | awk '{print $7}'`
txa=`expr "$tx1" '-' "$tx0"`
if [ $? -gt 1 ]
then
	echo "0 Expr error" >&2
	exit 1
fi
if [ "$txa" -lt "$count" ]
then
	# The buffer is probably big or sending slow on this kernel/card
	sleep 0.5
	tx1=`netstat -in -f link -I $oiface | tail -1 | awk '{print $7}'`
	txa=`expr "$tx1" '-' "$tx0"`
if [ $? -gt 1 ]
then
	echo "1 Expr error" >&2
	exit 1
fi
fi
rx1=`netstat -in -f link -I $iiface | tail -1 | awk '{print $5}'`
./bertest $count "$oiface" $payload 1
sleep 0.05
tx2=`netstat -in -f link -I $oiface | tail -1 | awk '{print $7}'`
txb=`expr "$tx2" '-' "$tx1"`
if [ $? -gt 1 ]
then
	echo "2 Expr error" >&2
	exit 1
fi
if [ "$txb" -lt "$count" ]
then
	# The buffer is probably big or sending slow on this kernel/card
	sleep 0.5
	tx2=`netstat -in -f link -I $oiface | tail -1 | awk '{print $7}'`
	txb=`expr "$tx2" '-' "$tx1"`
if [ $? -gt 1 ]
then
	echo "3 Expr error" >&2
	exit 1
fi
fi
rx2=`netstat -in -f link -I $iiface | tail -1 | awk '{print $5}'`
txb=`expr "$tx2" '-' "$tx1"`
if [ "$txa" -gt "$count" -o "$txb" -gt "$count" ]
then
	echo "Warning: other traffic is possibly mixing into the measurement. The \
result is shifted. \
tx is $txa and $txb instead of $count and $count." >& 2
fi
if [ "$txa" -lt "$count" -o "$txb" -lt "$count" ]
then
	echo -e "Error: the interface is unable to transmit. \
tx is $txa and $txb instead of $count and $count. This must be fixed as it means\
 totally invalid measurement.\nPossible causes:\n\
- nothink is connected to the card (the card doesn't see link integrity)
- network card not in full duplex\n\
- network card is receiving noise (weak signal on RX or bad RX)\n\
- network card is down (put up using ifconfig)." >& 2
exit 2
fi
lossa=`echo "scale=3; 100-($rx1-$rx0)*100/$count"| bc -l`
lossb=`echo "scale=3; 100-($rx2-$rx1)*100/$count"| bc -l`
echo -e "$date\t$lossa\t$lossb\t$count\t$nbits"
rx0=$rx2
tx0=$tx2
done